package com.citywithincity.db.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 唯一键,在插入的时候，需要判断唯一性,使用sql的插入判断
 * 目前，只支持一个
 * INSERT INTO customer(cm_acc, cm_pwd) 
 * SELECT '18659210057', NULL FROM DUAL 
 * WHERE '18659210057' NOT IN (SELECT cm_acc FROM customer);
 * @author Randy
 *
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Unique {
	
}
